The present invention relates in general to fluid filters and the selected design for connecting the filter to a mounting base or head. More specifically, the present invention relates to a spin-on filter that is constructed and arranged without using a nutplate for connecting the filter to a mounting base or head. By eliminating the nutplate, the resultant fluid filter is less expensive to fabricate, including cost savings by eliminating one of the component parts. A related benefit is the ability to have a mostly non-metallic construction for the fluid filter that in turn allows it to be considered “disposable” since it can be incinerated for disposal or recycled. By providing a construction that is incineratable, the structural mass of the filter can be reduced to low volume ash and this limits what will be added to landfills. The other option for “disposal” is to recycle the plastics used in the construction. Presently, when there is an all-plastic construction for the filter, it is generally described as having an “environmentally friendly green design”.
Typical spin-on fluid filters according to prior art designs are mounted to the head (spud) by the use of an internally-threaded metal nutplate. The nutplate is anchored to the fluid filter canister and includes at least one flow inlet and a flow exit cooperating with a centertube. The filter-to-head mounting includes a seal to prevent leakage between the head and the filter. Flow to the filter travels by way of the head and, once it is filtered, the fluid exits by way of the head. In order to fabricate a fluid filter using a nutplate, there are costs associated with the fabrication of the nutplate and costs associated with assembly of the nutplate into the fluid filter. If the nutplate could be eliminated from the fluid filter, these costs would be saved. While there may be, on a limited basis, other techniques used for connecting a fluid filter to a mounting head, one focus of the present invention is on the elimination of any nutplate from the fluid filter and thereby precluding use of a nutplate for connection to the head.
The present invention provides a fluid filter design that is capable of spin-on, threaded mounting to a head without using a nutplate. Instead, for the present invention, a threaded post is configured as part of the closed end of the canister and connects to a shaft (internally-threaded) that extends beyond the head into the spin-on filter. As will be described herein, the present invention includes various alternative embodiments. These embodiments include, among other features, fixing the shaft as part of the fluid filter, and connecting the shaft to a cooperating portion of the head. It should also be understood that the use of “spin-on” to describe the fluid filter of the present invention is intended to include not only threaded engagement, but other connection techniques, such as the use of a bayonet connection between the fluid filter and the mounting head. Related to a bayonet connection are quarter-turn and half-turn connections that may assume a variety of structural forms.
A typical prior art mounting head includes an externally-threaded post or portion that is received by the internally-threaded nutplate. For the preferred embodiment of the present invention, the design of the mounting head is changed and includes the internally-threaded shaft that extends axially all the way to the closed end of the canister so as to connect to the threaded post. Thus, for the present invention, not only does the spin-on filter design changed from the prior art, but the head design also changes.